1. Field of the Invention
The present invention relates to an opening device and to a procedure for opening the doors of an elevator.
2. Description of Related Art
The doors of present-day elevators mainly consists of double doors, the movable car being provided with a door or doors that move along with it, while the elevator shaft has separate doors at each landing. When the car is at a given landing, the doors of the car and those at the landing are opened simultaneously. In the elevator constructions currently used, simultaneous opening is implemented by providing the space between the car door and the landing door with so-called door coupling elements. These consist of suitable gripping elements mounted on the car door and of counter-elements mounted at a corresponding location on the landing door. Thus, when the car doors are moved using a power means provided on the car, the landing doors will be moved along with them.
The mutually corresponding parts of the door coupling apparatus are so arranged relative to each other that they can move past each other when the car is travelling in the elevator shaft, but when the car is at a landing and the car door is moving horizontally, said parts of the door coupling apparatus engage each other. Due to this mode of operation, corresponding parts of the door coupling apparatus must extend towards each other from the car door and from the landing door. Therefore, they require a certain space between the car and the landing. A corresponding space or gap is thus also formed between the car door sill and the landing door sill, and all traffic between the car and the landing must therefore pass over this relatively wide gap.
Another problem in existing door coupler systems is that, since the door coupling apparatus must unlock the landing doors before they can be opened, the car door has to be opened first e.g. by 10-20 mm, this motion causing the landing door to be unlocked, and it is only after this that the landing door can move along with the car door. This difference between the doors which appears at the beginning of the opening operation is maintained as long as the doors remain open, so that the width of the door actuating mechanism has to be increased by a corresponding amount.
In addition to the aesthetic drawback involved, the above-mentioned difference may cause problems in the operation of the capacitive safety edge of the elevator doors, because, due to said difference, the safety edge cannot "see" beyond the landing door. Thus, a blind space is formed between the doors, creating a potential danger to safe operation of the door.